Methods, devices and systems for draining fluid from the eye and/or for reducing intraocular pressure. A passageway (e.g., an opening, puncture or incision) is formed in the lamina cribosa or elsewhere to facilitate flow of fluid from the posterior chamber of the eye to either a) a subdural location within the optic nerve or b) a location within the subarachnoid space adjacent to the optic nerve. Fluid from the posterior chamber then drains into the optic nerve or directly into the subarachnoid space, where it becomes mixed with cerebrospinal fluid. In some cases, a tubular member (e.g., a shunt or stent) may be implanted in the passageway. A particular shunt device and shunt-introducer system is provided for such purpose. A vitrectomy or vitreous liquefaction procedure may be performed to remove some or all of the vitreous body, thereby facilitating creation of the passageway and/or placement of the tubular member as well as establishing a route for subsequent drainage of aqueous humor from the anterior chamber, though the posterior chamber and outwardly though the passageway where it becomes mixed with cerebrospinal fluid.